1. Field of the Invention
The present invention relates to a magnetic head suspension for supporting a magnetic head slider that reads and/or writes data from/to a recording medium such as a hard disk device.
2. Related Art
A magnetic head suspension for supporting a magnetic head slider is required to move the magnetic head slider with high accuracy to a desired track of a recording medium such as a hard disk device (improvement in positioning accuracy), as well as to be highly impact-resistant in a state where the magnetic head suspension is in an operating condition in which the magnetic head slider is positioned above the recording medium (improvement in impact resistance).
In order to realize the improvement in positioning accuracy, the magnetic head suspension is required to be resistant to have a vibration that causes the magnetic head slider to displace from the desired track. In particular, it is crucial to raise a resonant frequency in a sway mode that is a main resonance mode.
For example, it is possible to raise the resonant frequency in the sway mode by increasing a thickness of a load beam part, which serves as one of components of the magnetic head suspension, so as to increase rigidity of the load beam part in an off track direction.
It is also possible to increase rigidity of the load beam part in the off track direction by increasing a width of a proximal end of the load beam part so as to increase a distance between support points at which the load beam part is supported.
Specifically, the magnetic head suspension includes a load bending part that generates a load for pressing the magnetic head slider toward a disk surface, the load beam part that transfers the load to the magnetic head slider, a supporting part such as an arm that supports the load beam part with the load bending part interposed therebetween, and a flexure part that is joined to the load beam part and that supports the magnetic head slider.
In general, the load bending part is formed of an elastic plate that is elastically bendable in a z direction orthogonal to the disk surface of the recording medium.
More specifically, the elastic plate has a proximal end connected to the supporting part and a free end connected to the proximal end of the load beam part, so that the load beam part is supported by the elastic plate in a cantilevered manner.
In this configuration, it is possible to increase rigidity of the load beam part in the off track direction by increasing the width of the proximal end of the load beam part so as to increase the distance in a suspension widthwise direction between the support points at which the load beam part is supported by the load bending part (connecting points between the load beam part and the free end of the elastic plate).
However, both of increase in thickness of the load beam part and increase in width of the proximal end of the load beam part result in increase in weight thereof, which adversely affects impact resistance of the magnetic head suspension.
Specifically, improvement in impact resistance requires that the magnetic head suspension is resistant to be displaced in the z direction orthogonal to the disk surface of the recording medium in a case where an extraneous impact force is applied to a data storage device that is mounted with the magnetic head suspension.
In particular, if an extraneous impact of not less than a predetermined force in a direction of moving the magnetic head slider apart from the disk surface is applied to the data storage device so that the magnetic head slider is moved apart from the disk surface (jumping action), the magnetic head slider may swing back from the jumping action to hit and damage the disk surface.
Impact resistance can be effectively improved by reducing the thickness and/or the width of the load beam part and thereby reducing the weight thereof, so as to reduce an inertial force that is applied to the load beam part upon application of an impact force. Impact resistance is rather deteriorated by increase in thickness and/or width of the load beam part for a purpose of raising the resonant frequency of the magnetic head suspension.
There are proposed some configurations for improving impact resistance of the magnetic head suspension with the thickness and/or the width of the load beam part being unchanged. Namely, Japanese Unexamined Patent Publication No. 2004-348804 discloses a configuration (hereinafter, referred to as a first conventional configuration) in which a component forming the load beam part is provided with a proximal-end-side extended region that is extended beyond the load bending part toward the proximal end side. Further, Japanese Unexamined Patent Publications Nos. 09-082052 and 11-039808 each disclose a configuration (hereinafter, referred to as a second conventional configuration) in which the proximal end of the load beam part is provided with an equilibrating weight.
In the first and second conventional configurations, the proximal-end-side extended region and/or the equilibrating weight equilibrate(s) as much as possible the weight on the distal end side and the weight on the proximal end side of the magnetic head suspension with the load bending part as a reference, so that the magnetic head slider is inhibited from jumping upon application of an extraneous impact force. These configurations are useful in that they do not deteriorate rigidity of the load beam part.
However, in the first and second conventional configurations, the load beam part is joined to the free end of the load bending part that is supported by the supporting part in a cantilevered manner. In this configuration, the support points at which the load beam part is supported (joining points between the load beam part and the load bending part) are dramatically displaced in the z direction orthogonal to the disk surface upon application of an impact force.
Therefore, the magnetic head suspension according to each of the first and second conventional configurations does not deteriorate rigidity of the load beam part, but does not adequately improve impact resistance thereof.